PROJECT ABSTRACT Reports estimate nearly 2 million unaccompanied homeless youth aged 13-24 in the United States each year.1 Nearly 40% of these youth were formerly a part of the foster care system.2 Research has demonstrated that homeless youth are at elevated risk for HIV3-10 and a separate body of research has reported elevated risk for HIV among foster and former foster youth.11-14 Thus, the accumulation of risk factors common to both homeless youth and former foster youth place this large population of homeless former foster youth in the nexus of life experiences that position them at extreme risk for engaging in a number of HIV risk behaviors, and necessitating an increase in intervention research to address the unique needs of this population. While interventions targeting HIV prevention efforts have focused on homeless youth, little research has focused on the impact of unique foster care experiences on HIV risk behaviors. And because studies have begun to discover the role of foster care in network disruption and network engagement10 and we know that HIV risk behaviors are impacted by network engagement,30 a need exists to better understand the network characteristics of homeless young adults with a history of foster care and associations between these characteristics, and HIV-risk behaviors. While current studies have examined some HIV risk behaviors by foster care status,10 limitations in the current data do not reflect the heterogeneity of foster care experiences. Based on our knowledge of the impact of networks on HIV risk behaviors, and the lack of research on the impact of foster care experiences on network engagement, the current state of the literature lacks a focus on the unique experiences of homeless former foster youth, and the ways these experiences impact network engagement and HIV risk behaviors, in order to better inform and adapt HIV interventions for homeless youth. The study?s goals include drastically increasing knowledge regarding HIV risk among homeless former foster youth. This study proposes primary data collection of a sample of homeless youth with a history of foster care, utilizing the data collection site and methods used in the quantitative survey data and social network data from an NIMH-funded R01 study (MH903336; PI: Rice). The use of primary data will provide a unique contribution to the literature and increase our understanding of the impact of foster care experience and network engagement on HIV risk among homeless youths. These findings will be used to inform new directions in homeless youth interventions; specifically what network-level interventions could be adapted to prevent HIV risks in the homeless former foster youth population. Training goals include in-depth coursework and mentoring to apply the findings of these results to intervention adaption and development focused on network-based HIV interventions for homeless former foster youth.